Programmable logic devices are semiconductor integrated circuits capable of reconfiguring circuits after chip manufacture. A programmable logic device includes a plurality of wiring lines, of which two selected wiring lines are electrically connected or disconnected. Some methods are present to control the connection or disconnection of the two selected wiring lines.
One method uses transistors and memories. The memories are electrically programmable, and the transistors are turned on or off based on the data stored in the memories. Two-terminal resistive change memories are known as the aforementioned memories. Each resistive change memory includes two electrodes and a resistive change layer disposed between the two electrodes. The resistive state of the resistive change memory is changed by applying a predetermined voltage between the two electrodes, thereby switching the resistance between the two electrodes from one of a low-resistance state and a high-resistance state to the other.
Such known programmable logic devices using resistive change memories have the following problem. When a programmable logic device is in operation, a power supply voltage (for example 1.5 V) is applied between the electrodes of the resistive change memory. If the power supply voltage is higher than the voltage at which the resistive state of the resistive change memory is switched, the data stored in the resistive change memory may be rewritten by the application of the power supply voltage. This may cause a malfunction of the circuit.